Apparatus for condensing shipboard cargos of vaporizable liquid



May 8, 1962 J. w. L. KOHLER ETAL 3,033,003

APPARATUS FOR CONDENSING SHIPBOARD CARGOS OF VAPORISABLE LIQUID Filed Feb. 2. 1960 FIG-1 INVENTOR .W. KOHLER X.A. DROS J.A.L. IJZER BY ,5. e

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United States Patent 3,033,903 Patented May 8, 1962 ice 3,033,003 APPARATUS FOR CONDENSING SHlPBOARD CARGOS F VAPORIZABLE LIQUID Jacob Willem Laurens Kiihler, Albert August Bros, and Jacobus Albertus Louisa Ijzer, Eindhoven, Netherlands, assignors to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Feb. 2, 1960, Ser. No. 6,248 Claims priority, application Netherlands Nov. 18, 1959 4 Claims. (CI. 62-54) This invention relates to vessels, more particularly ships, comprising cargo-holds or tanks, for a'vaporisable or gasifiable liquid, such as liquid methane.

Such tankers are now in the course of development for the transport of liquid gas or liquid vapour frequently over long distances.

During transport, gas or vapour is produced in the tanks due to radiation of heat, which gas or vapour under certain conditions requires to be carried off and is frequently to be regarded wholly or in part as lost. It has previously been suggested for such gas or vapour to be used, at least in part, for example as a fuel for the engines driving the ship or for a gas turbine driving an air-compressor.

It has also been suggested to cause condensation of the vapour or the gas by means of compressor-expansion machines and interposed heat-exchangers and possibly con-l densers.

The present invention adopts another method which affords important economic advantages.

According to the invention, at least one cold-gas re frigerator is provided for condensing vapour or gas produced in the holds. 7

The term cold-gas refrigerator is to be understood herein to mean a refrigerator operating on the reversed hot-gas motor principle. In sucha refrigerator, a gas which is invariably in the same state of aggregation, traverses a closed thermodynamic cycle. Such a refrigerator comprises at least two chambers, the volumes of which may be varied, for example by means of piston-like bodies, with a substantially constant phase difference.

However it is alternatively possible to provide the engine with other means for varying the volumes, such as bellows or diaphragms. The gas is substantially compressed in one of the chambers of variable volume whereas the gas is substantially expanded in another chamber. These chambers will be referred to hereinafter as the compression chamber and the expansion chamber, respectively. The chambers of variable volumes freely communicate with each other via a first heat-exchanger, a regenerator and a second heat-exchanger.

The heat-exchanger which communicates with the corn pression chamber has heat dissipated from it, for example by Water-cooling or air-cooling, this heat-exchanger frequently being referred to as the cooler, whereas the heat-exchanger which communicates with the expansion chamber has heat supplied to it at a low temperature, this heat-exchanger frequently being referred to as the freezer.

Such a cold-gas refrigerator may be designed so that the cold is delivered at a temperature of even 200 C. The difference in the temperatures bet-ween the freezer and the cooler may be bridged in one step.

A cold-gas refrigerator may be designed in different ways, for example as a displacer engine, as a double-acting engine, as an engine the cylinders of which are at an angle to one another, or as an engine the working chamber of which is combined with that of a hot-gas motor.

The essence of the invention is that a cold-gas refrigerator of this very type is admirably suited to be used on board a ship having the above-mentioned characteristics for condensing the vapour or gas emanating in the cargohold or tanks.

The cold-gas refrigerator may also be proportioned and arranged so as to be capable of contributing, at least considerably, to the cooling of tanks which are empty wholly or in part. This function is thus usually fulfilled by the cold-gas refrigerator during the home voyage of the ship to the place where again liquid gas is loaded. If desired, the cold-gas refrigerator may then produce liquid air or liquid nitrogen which is used for cooling the tanks. In order to supplement the cooling process, it is possible, if desired, to keep some cold, vaporisable liquid, such as liquid methane, in the tanks.

In on important embodiment of the invention, the cold-gas refrigerator may be arranged on the ships deck; This is possible because a cold-gas refrigerator can. be easily balanced and is then free from vibration.

One cold-gas refrigerator may be provided for each tank. It is to be noted that it is necessary for installations of known type to have the character of a central aggregate to ensure that the useful output satisfies reasonable requirements.

The cold-gas refrigerator does not require such a central aggregate. Even when several cold-gas refrigerators are arranged in decentralised positions, the useful output of the smaller components remains substantially equal to that of a central aggregate. However, it is alternatively possible for the cold-gas refrigerator to deal Witha'plurality of tanks, for example two or three, for condensation purposes. In this case it is advantageous to provide a device for distributing the condensate delivered by one or more cold-gas refrigerators among the tanks communicating with the cold-gas refrigerator. Such a distribution may take place as a function f factors determined by the flow of gas or vapour led from the tanks to the cold-gas refrigerator, for example by the level of the liquid in the tanks.

It is possible to arrange the cold-gas refrigerator in an additional chamber which communicates through a gas supply duct and a condensate discharge duct with one or more tanks.

A very simple arrangement is obtained if the cold head of the cold-gas refrigerator extends into a cargo-hold or tank, which usually amounts to the cold head of the coldgas refrigerator extending downwards through the ships deck. This is a possibility which the cold-gas refrigerator permits.

A hot-gas motor may be provided for driving the coldgas refrigerator. The combustion device of the hot-gas motor may then be fed on a combustible mixture of the vapour or the gas of the liquid transported in the tanks, and air. This may be a combined engine.

The useful output of a ship comprising an installationof cold-gas refrigerators has been found to he certainly not lower than that of a ship provided with an installation for recondensing gas or vapour, which operates on different principles. A very important factor in this connection is that the cost of an installation of cold-gas refrigerators and also the working cost thereof may be less than that of installations of known type.

The cold-gas refrigerators may be continuously in operation for a very long period.

The tanks of the ship may either be designed as communicating vessels or provided, at their upper sides, with overflow devices.

It is advantageous to provide spare cold-gas refrigerators to enable a certain number of cold-gas refrigerators to be continuously in operation. Aggregates may be provided, for example of the type having four cylinders, two

of which operate as a cold-gas refrigerator and the other two of which operate as a driving motor of the hot-gas type. Such an aggregate may have the same crank drive for all the pistons and displacers so that there is no shaft xtending to the exterior. It is also possible to use ag- 3 gregates having, for example, six or eight cylinders, three or four of which serve as motor cylinders.

When using such multi-cylinder engines, it is possible to provide several tanks with their own condensing cold heads, so that one multi cylinder engine deals with a plurality of tanks fully separately and regulating difliculties cannot occur.

Preferably, a single pipe line from the tank to the engine is used for supplying vapour or gas to be condensed to the cold head of the engine and also for discharging the condensate produced.

The pressure in the tank may be used for controlling the cold-gas refrigerator.

The use of a cold-gas refrigerator in the manner according to the invention has the important advantage that the cold-gas refrigerator may be employed without modification as a vaporizer for the liquid gas during unloading, the engine being able to deliver power to the shaft, which may result in delivery of current for the loading and unloading pumps and into the mains.

In order that the invention may be readily carried into effect, four embodiments thereof will now be described in detail, by way of example, with reference to the accompanying diagrammatic drawing.

FIG. 1 shows a cross-sectional view of a ship. A cold head 2 of a cold-gas refrigerator 1 extends through a deck 3 into a cargo-hold 4. Gas or vapour produced in the hold is brought into contact with the cold head and caused to condense there.

FIG. 2 shows in what manner a cold-gas refrigerator 1 may be arranged between two tanks 4 and 5 on the deck 3. Ducts 6 and 7 lead to the cold head 2 of the cold-gas refrigerator. Condensate produced adjacent the cold head 2 is distributed, for example as a function of the pressure prevailing in the ducts 6 and 7, over ducts 8 and 9 and led back to the tanks 4 and 5. The cold-gas refrigerator may be driven in a simple manner by means of an electric motor. Cooling water is to be supplied to the cold-gas refrigerator through a duct 10.

FIG. 3 shows a tank 4 which communicates through an additional space or spout 11 with the cold head 2 of cold-gas refrigerator 1, which extends through the wall of the additional space.

FIG. 4 illustrates in What manner a tank communicates through a single duct 12 with the cold head 2 of a coldgas refrigerator 1.

The duct 12 serves both to supply gas or vapour to be condensed to the head 2 and to discharge condensate produced by the head to the tank 4.

What is claimed is:

1. Apparatus for condensing shipboard cargos of vaporisable liquid stored in a tank comprising at least one cold gas refrigerator working on the reversed Sterling cycle being provided with a cold head which extends into the interior of said tank and directly condenses the vapors from the liquid stored therein.

2. Apparatus for condensing shipboard cargos of vaporisable liquid stored in tanks comprising at least one cold gas refrigerator Working on the reversed Sterling cycle being provided with a cold head in contact with the vapors of said liquid for directly condensing said vapors, and a hot-gas motor for driving said cold gas refrigerator, the fuel for said hot gas motor being supplied from the vapor of the liquid stored in said tanks.

3. Apparatus for condensing ship-board cargos of vaporisable liquid stored in tanks comprising a multicylinder cold-gas refrigerator working on the reversed Sterling cycle being provided with cold heads in contact with the vapors of said liquid for directly condensing said vapors fro-m the liquid stored therein, and the resultant condensate being divided and separately directed to each of said tanks.

4. Apparatus for condensing vapors of a liquid methane cargo stored in a tank comprising at least one cold gas refrigerator working on the reversed Sterling cycle being provided with a cold head which extends into the interior of said tank and directly condenses the vapors from the liquid methane stored therein.

References Cited in the file of this patent UNITED STATES PATENTS 2,550,886 Thompson May 1, 1951 2,753,691 Wissmiller July 10, 1956 2,836,964 Roosendaal et a1. June 3, 1958 

